For 2023 (and 2024 ...) - we are now fully retired from IT training. We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
Sorting arrays and hashes in Ruby
In Ruby, you can use the sort method on an array to sort that array - but you cannot sort a hash. That's because of the techniques used within a hash to make it very fast to look up individual elements.
So what do you do if you want to sort something like this: ?
stuff = {"Steve" => "Kent", "Graham" => "Wiltshire",
"Chris" => "Wiltshire", "Betty" => "Windsor",
"Fred" => "Aberstwyth", "Harry" => "Potteries",
"Sarah" => "Wiltshire"}
You get an array of the keys (using the keys method on the hash), and then you sort the list. To output the pairs from the hash in order, you step through the hash in the order given in the list and the job is done!
There's an example [here] in the examples directory - a piece of code I wrote as a demonstration during this week's Ruby Programming Training Course.
(written 2010-01-30)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles R107 - Collections (Arrays and Hashes) in Ruby [991] Adding a member to a Hash in Ruby - (2006-12-16) [2291] Collection objects (array and hash) in Ruby - (2009-07-16) [2618] What are Ruby Symbols? - (2010-02-02) [2621] Ruby collections and strings - some new examples - (2010-02-03) [2976] Creating, extending, traversing and combining Ruby arrays - (2010-09-30) [3253] Is this number between? Does this list include? - Ruby - (2011-04-18) [3255] Process every member of an array, and sort an array - Ruby - (2011-04-21) [3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23) [3435] Sorta sorting a hash, and what if an exception is NOT thrown - Ruby - (2011-09-12) [3757] Ruby - a teaching example showing many of the language features in short but useful program - (2012-06-09) [4368] Shuffling a list - Ruby and Python - (2014-12-28) [4499] Significant work - beyond helloworld in Ruby - (2015-05-27) [4502] Reading and parsing a JSON object in Ruby - (2015-06-01)
Some other Articles
Cheat Sheet - what do you need for Ruby on Rails?Scope of variables - important to Ruby on RailsSearch and replace in Ruby - Ruby Regular ExpressionsAnswers on Ruby on RailsSorting arrays and hashes in RubyRuby on Rails - a sample application to teach you howTips for writing a test program (Ruby / Python / Java)Ruby objects - a primerEast of Melksham - Building Work StartsRuby - is_a? v instance_of? - what is the difference?
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This is a page archived from The Horse's Mouth at
http://www.wellho.net/horse/ -
the diary and writings of Graham Ellis.
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releases, price changes, new techniques. Please check back via
our main site for current courses,
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